Learn · Drug testing
Cannabis and drug tests, explained with sources.
What each test looks for, how long it can detect cannabis, and what a result does and doesn't mean. Every number on these pages links to a clinical study, lab reference, or federal guideline.
| Test | Looks for | Typical window |
|---|---|---|
| Urine | THC-COOH (metabolite) | ~3 days (single use) to 30+ days (chronic heavy use) |
| Blood | THC and metabolites | Often 1–2 days; weeks in some daily users |
| Saliva | THC | Hours to ~1–3 days after a single use |
| Hair | THC, THC-COOH | ~3 months; reliable mainly for heavy use |
Guides
How long weed stays in your system
Detection windows for urine, blood, saliva, and hair, by how often you use.
Urine drug tests
Federal cutoffs, how screening and confirmation work, and windows by frequency.
Blood tests
Why blood reflects recent use, and why daily users can stay positive for weeks.
Saliva (oral fluid) tests
Federal oral fluid cutoffs and why saliva tracks recent use.
Hair tests
The 3-month window, why light use is often missed, and contamination limits.
CBD and drug tests
Why pure CBD rarely registers, and why full-spectrum products can.
Related: cannabis side effects · drug interactions · employment & drug-testing law by state · cannabis laws by state
NOTE Informational only — not medical or legal advice. Cannabis affects everyone differently; consult a qualified professional. Verify current details with an official source. Last reviewed 2026-10-03.